MDSC-2013 users training_Part4

MDSC Training Course
Characterization of Proteins

In reality, the problem of measuring the Tg of proteins is more practical than theoretical:

The glass transition is very broad and stability of the DSC baseline is critical
MDSC Training Course
Quantification of DCp at Tg
With High Volume Pans
1. 2.
3.
4.
5.
Calibrate Reversing Cp signal of MDSC using sapphire Measure heat capacity of protein at room temperature using optimum conditions Aluminum crimped pan and 100sec period Measure heat capacity of protein at room temperature using conditions that will be used for measuring Tg (stainless steel pans, 200 sec period etc) Determine new Reversing Cp calibration constant for large pans that provides accurate measurement of absolute Cp Run sample using new Reversing Cp calibration constant
Quantification of DCp at Tg
Isothermal Measurement of Rev Cp for Casein Protein Using High Volume Stainless Steel Pans
MDSC Training Course
Optimizing MDSC Experimental Conditions
MDSC Training Course
DSC Data Ramp After MDSC @ 50°C
Comparison of Cool & Heat Data on 50:50 Mix of Acetylsalicylic Acid and Mag Stearate After 100 Hours at 50°C
o
Solution; Modulated DSC®
Solution; High volume (100ul) stainless steel pans Solution; High volume pans provide hermetic sealing Aluminum hermetic pans will typically allow water evaporation to occur at temperatures above 110°C and this hides the lower energy glass transition
Optimized MDSC Results for Casein Protein
MDSC Training Course
MDSC of Albumin – 1st Heat
MDSC Shows Broad Tg and an Endothermic Process at Tg
MDSC Training Course
MDSC Training Course
MDSC Confirms No Interaction
Acetylsalicylic Acid and Crystalline Sucrose Show No Incompatibility at 50°C
Drift in Reversing Cp Over 100 Hours is Approx. +/- 0.001 J/g°C
MDSC Training Course
Comparison of Data
Comparison of MDSC Isothermal Data at 50°C on 50:50 Mixtures of Acetylsalicylic Acid with Mag Stearate and Sucrose

Large samples are required for improved sensitivity
o

Water content must be maintained
o o
MDSC Training Course
MDSC Approach to Measuring Tg of Proteins
High Volume Stainless Steel Pans Permit Large Samples and Prevent Moisture Loss
MDSC Training Course
Tg & Cp for Casein Protein
20.0°C 1.33J/(g°C)
MDSC Training Course
MDSC Training Course
MDSC Analysis of Acetaminophen
Acetaminophen 13.68mg MDSC 1/50@2
MDSC Training Course
enerally accepted by the pharmaceutical industry that the glass transition of solid proteins can not be measured by DSC due to:
Human Incompatibility??
MDSC Training Course
Miscellaneous

Using Baseline Subtraction When Measuring Absolute Values of Crystallinity

All DSC instruments have some curvature in the baseline. This curvature can cause substantial errors when integrating peaks over a wide temperature range. To correct for baseline curvature;
MDSC Training Course
DSC Data Ramp After MDSC @ 60°C
DSC Data Confirms Formation of Crystalline Structure in 50:50 Mix of Acetylsalicylic Acid and Magnesium Stearate : 60°C for 12 Hours Crystallization confirms that significant crystalline structure was lost during 12 hours at 60°C
MDSC data showed that some crystalline structure formed during 12 hours at 60°C
MDSC Training Course
Still Interacts at 50°C
Acetylsalicylic Acid and Aspirin Tablet Interact Immediately with Magnesium Stearate Even at 50°C
Drift in Heat Flow Over 100 Hours is Approx. +/15 microWatts
MDSC Training Course
DSC After MDSC @ 50°C
DSC Cool/Heat Data on 50:50 Mixture of Acetylsalicylic Acid and Crystalline Sucrose Confirms No Interaction After 100 Hours at 50°C
MDSC Training Course
MDSC Data Shows Interaction
Isothermal @ 122°C
MDSC Training Course
Salbutamol Hemisulfate
MDSC Results Show Salbutamol Hemisulfate Is Stable at 122°C But a 50:50 Mixture With Sucrose Is Unstable

Use high volume, hermetic stainless steel pans to:

Increase size of sample (25-50mg) Prevent moisture loss over the required temperature range to 170°C
MDSC Raw Data Signals
Crystalline Drug Monohydrate 3.75mg (pinhole) MDSC .159/60@1
MDSC Training Course
CP Signals Show Changes in Structure
Crystalline Drug Monohydrate 3.75mg (pinhole) MDSC .159/60@1